Prosthetic heart valves are usually implanted in the human heart to replace natural valves. These valves essentially function as check valves, permitting the blood to flow through the valves in a downstream direction, but blocking blood flow in a reverse or upstream direction. Some prosthetic heart valves include an annular valve housing or body with a central orifice and occluders. The orifice provides a passageway for the blood, and the occluders open and close to regulate the passage of blood. For instance, U.S. Pat. Nos. 5,876,436 and 6,719,790 describe in detail specific prosthetic heart valves. Both of these references are hereby incorporated herein by reference in their entireties.
Certain prosthetic heart valves are collapsible to a relatively small circumferential size. This kind of prosthetic heart valve can be delivered into a patient less invasively than valves that are not collapsible. For example, a collapsible valve may be delivered into the patient via tube-like delivery apparatus such as a catheter, a trocar, a laparoscopic instrument, or the like. This can avoid the need for a more invasive procedure such as full open-chest, open-heart surgery. When the collapsed valve has reached the desired implant site in the patient (e.g., at or near the annulus of the patient's heart valve that is to be effectively replaced by the prosthetic valve), the prosthetic valve can be re-expanded to full operating size and released from the delivery apparatus. Typically, in its full operating size, the prosthetic valve engages adjacent native tissue of the patient to firmly anchor itself in the patient.
Because valves of the type described above are basically implanted by remote control (because the valve is inside the patient at the far end of delivery apparatus that is manipulated and controlled from its proximal end outside the patient), it can be difficult to get the valve to exactly the right location in the patient before releasing it from the delivery apparatus. Improvements are therefore sought with respect to how such valves are deployed, e.g., so that the valve can be repositioned and/or differently deployed if deployment does not appear to be leaving the valve exactly where and how it should be deployed.